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BIC 1 acts as a transcriptional coactivator to promote brassinosteroid signaling and plant growth
Author(s) -
Yang Zongju,
Yan Baiqiang,
Dong Huixue,
He Guanhua,
Zhou Yun,
Sun Jiaqiang
Publication year - 2020
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.2020104615
Subject(s) - chinese academy of sciences , beijing , china , agriculture , crop , key (lock) , geography , political science , biology , forestry , ecology , archaeology
The BRASSINAZOLE ‐ RESISTANT 1 ( BZR 1) transcription factor family plays an essential role in plant brassinosteroid ( BR ) signaling, but the signaling mechanism through which BZR 1 and its homologs cooperate with certain coactivators to facilitate transcription of target genes remains incompletely understood. In this study, we used an efficient protein interaction screening system to identify blue‐light inhibitor of cryptochromes 1 ( BIC 1) as a new BZR 1‐interacting protein in Arabidopsis thaliana . We show that BIC 1 positively regulates BR signaling and acts as a transcriptional coactivator for BZR 1‐dependent activation of BR ‐responsive genes. Simultaneously, BIC 1 interacts with the transcription factor PIF 4 to synergistically and interdependently activate expression of downstream genes including PIF 4 itself, and to promote plant growth. Chromatin immunoprecipitation assays demonstrate that BIC 1 and BZR 1/ PIF 4 interdependently associate with the promoters of common target genes. In addition, we show that the interaction between BIC 1 and BZR 1 is evolutionally conserved in the model monocot plant Triticum aestivum (bread wheat). Together, our results reveal mechanistic details of BR signaling mediated by a transcriptional activation module BIC 1/ BZR 1/ PIF 4 and thus provide new insights into the molecular mechanisms underlying the integration of BR and light signaling in plants.